The present invention relates to a cutting blade for use in a rotary lawnmower. More particularly, the present invention relates to a low noise, rotary cutting blade which functions as a backward curved centrifical fan to provide a good upward and outward flow of air.
In order for a rotary lawnmower to provide a good, even cut of grass, the cutting blade must generate a substantial flow of air upwardly into the blade housing. This upward flow of air stands the grass up to be in position to be cut by the blade. Otherwise, an even cut will not be achieved. Also, the blade must generate a substantial flow of air from the interior of the housing outwardly into, for example, a grass collecting bag. This flow of air is necessary to transport the grass clippings outwardly from the interior of the housing so that the clippings do not accumulate therein and interfere with the rotation of the cutting blade.
Unfortunately, with conventional blades, high speeds of blade rotation must be used to obtain the aforementioned air flows. At such high speeds of rotation a certain amount of irritating and bothersome noise is generated. Hence, it would be desirable to have a cutting blade which develops a substantial flow of air even at a relatively slow speed of rotation. Further, it would be desirable to have a cutting blade which is quiet in operation.